1. Field of the Invention
This invention relates to locks and more specifically to locking mechanisms mountable on the king pins of semitrailers.
Semitrailers full of cargo are frequently stolen by dishonest parties because the semitrailers must often be left unattended for several hours or are located in an area where it would not seem unusual for a tractor to connect to and depart with a semitrailer. The present invention was made in order to severely deter such semitrailer theft by providing an effective portable locking mechanism which attaches to the semitrailer king pin and which is of a convenient size and weight.
2. Description of Prior Art
In the prior art, there are several locking devices, all of which employ movement of a lock bar against the recessed portion of a king pin such that the motion of the lock bar is at a right angle to the king pin. In addition, to prevent removal of the lock bar in the event the key lock mechanism itself is removed, various devices have been proposed which are built into the main body and which must themselves move and which are therefore subject to being adversely affected by dirt, grease, and other foreign matter common to the environment in which the lock is used. These additional moving parts also make the locks more difficult and expensive to manufacture. In addition, these moving parts must be periodically dismantled and cleaned to insure continued proper performance.
The present invention provides a secure lock which is unique in its orientation of the lock bar with respect to the king pin and which is also unique in the operation of the lock bar itself. The lock bar cannot move along its longitudinal axis and cannot therefore be removed even if the cylinder lock mechanism is removed. Except for the cylinder lock mechanism, the lock bar is the only portion of the lock which moves. The lock bar motion is purely rotational and is therefore less subject to the jamming effects of dirt and other debris common to its environment. It is also unique in that the only way to remove the lock is to rotate the lock bar a full one hundred eighty degrees. Rotation of the lock bar through an angle less than one hundred eighty degrees will allow the lock bar to maintain a locking effect on the king pin.